Progress report on neutron beam experiments at Dalat Research Reactor

The conduct and the utilizations of neutron beams at Dalat Nuclear Research Reactor was reported. In 1998 and 1999 the filtered thermal neutron beam at the beam tube using substances Si, Ti, C, Pb was extracted. The investigations on physical characteristics of reactor; neutron spectra and fluxes at beam tube; safety conditions have been carried out by calculations and experiments. The physical characteristics for the purposes of prompt gamma neutron activation analysis (PGNAA) and nuclear data measurement were improved. The delayed neutron analysis method is used to detect the neutron emission fragments produced by neutron irradiation of uranium and thorium. This method is to determine the concentrations of uranium and thorium simultaneously and detect 10-6 g of uranium and 8x10-6 g thorium in 10 g sample with a precision of 8 per cent. Beside the delayed neutron analysis facility, a gamma spectrometer system with HP-Ge 90 cm3 semiconductor detector was installed at pneumatic transfer for cyclic activation analysis (CAA). The CAA method has given analytical results quickly and sensitively for the isotopes with half-lives in order of seconds to minutes. (author)